As a system for protecting an occupant in the event of a car collision, Japanese Unexamined Patent Application Publication No. 10-217818 describes an occupant protection system in which an inflatable airbag is disposed between a seat cushion and a seat pan, and the front part of the seat cushion is pushed up by inflating the airbag in a car collision to prevent a submarine phenomenon such that the occupant passes under a lap belt in a front collision, even with a seatbelt in use.
FIG. 6 is a longitudinal sectional view of the occupant protection system of the reference, along the length of the seat. An airbag 44 is disposed between a cushion frame 40 and a seat pad 42 in the front of the seat. The airbag 44 extends along the lateral width of the seat and is inflated by an inflator (gas generator) 46. The upper surface of the seat pad 42 is covered with a trim cover 48, on which an occupant sits.
When the inflator 46 is activated in case of a vehicle collision, the airbag 44 inflates, so that the front part of the seat pad 42 is pushed up or tossed from below to increase in density, thereby preventing the forward movement of the body of an occupant (including restraining).
While the inflator (gas generator) 46 is disposed in the airbag 44 in the reference, the gas generator can be disposed outside the airbag to moderate the heat-resistance requirement for the airbag. In this case, the gas generator and the airbag are joined together with a duct, through which gas from the gas generator is introduced into the airbag.
In joining a gas generator with a duct, the gas generator is preferably of a type having a gas port at the distal end. This type of gas generator generally has the gas port at the side circumferential surface of the distal end. In this case, when the gas generators emit a jet of gas, the gas issues out from the distal end of the gas generators radially, or in non-axial directions relative to the duct, so that the gas flows less smoothly into the depth in the airbag (a portion furthermost from the duct).